An electric walk behind greens mower has a horizontally aligned reel cutting unit that is designed to provide a high quality cut on golf course greens. In the past, some walk-behind greens mowers have been battery powered and/or have used electric motors to rotate the cutting reels and traction rollers or drums. For example, British Patent 985287 relates to a battery-electric mower having separate electric motors for driving the cutting reel and traction roller. Other examples of electric walk behind greens mowers include those manufactured and sold by Atco since the 1950s.
U.S. Pat. Nos. 6,523,334 and 6,758,030 for Battery-powered walk-behind greens mower relate to variable controls such as potentiometers that an operator may use to control the speed of a traction motor and a reel motor. The traction drive may be interrupted by releasing a bail which actuates a switch. The reel motor may be shut down if an electric sensor senses a predetermined low voltage in the battery. The traction or reel motors also may be shut down if sensors built into the motors sense current or heat exceeding predetermined limits. A battery cutout relay may terminate current to the reel motor through an electric contactor. Additionally, closing the key switch activates a time delay module that provides an electrical shutdown system. After a specified time period of non-operation, the time delay module removes power to the entire system.
U.S. Pat. No. 7,007,446 for Battery-powered walk-behind greens mower relates to a greens mower having a controller that communicates with a battery level indicator, card reader and operator presence control system to determine the mode of operation, and to supply or discontinue electrical current to a reel motor and/or traction motor. The controller includes an internal soft start module that limits current applied to the reel motor during start up.
U.S. Pat. No. 7,111,443 for Walk reel mower with electric drive and automatic slow down system relates to a system for automatically slowing a greens mower during turns. A switch may be actuated when the operator pushes down on the handle to lift the reel cutting unit up off the ground, causing a rearward pitching motion of the reel cutting unit. The switch is connected to a motor controller that automatically decreases power flowing from the battery to the traction motor by a predetermined increment.
U.S. Pat. No. 7,168,227 for Internal combustion engine traction drive with electric cutting unit drive for walking greens mower relates to a greens mower controller that controls the rotational speed of an electric reel motor in relation to the detected drive speed of one or more rollers.
U.S. Pat. Nos. 7,367,173 and 7,610,738 for Greens mower data display and controller relate to a mower controller coupled to a data display and controls reel speed and groundspeed. The mower controller may receive groundspeed data from the traction drive system or a sensor coupled to one or more rollers, and reel motor speed and current draw from the cutting reel and motor. The mower controller may disengage the electric motor upon detection of a current spike caused by a jam, or during motor overload or overheating. Mower controllers on several mowers may communicate with a master controller.
U.S. Pat. No. 7,954,308 for Frequency of clip adjustment system and method for reel mower cutting unit relates to a system for adjusting frequency of clip. A reel motor controller determines the required reel speed based on the walk speed, frequency of clip setting from a user interface, and one or more numerical constants specific to the reel mower cutting unit.
U.S. Pat. No. 8,572,940 for Mower with thumb wheel throttle control relates to an electric walk behind greens mower with a thumb wheel that progressively increases and decreases power output of an engine or rotates a potentiometer shaft to change the speed of an electric motor.
U.S. Pat. No. 8,660,744 for Speed control system for walk behind powered equipment relates to operator hand controls used to set the speed of a traction roller. A controller and display may be used to set minimum and maximum speeds of the traction and reel motors.
Walk behind greens mowers that use battery power for electric reel and traction motors are effective to reduce noise and minimize fluid leakage problems, but still may be difficult to operate without long experience or training. For example, walk behind greens mowers with electric traction motors may pull forward suddenly if an operator grips the bail or releases the park brake, but has not set the speed control lever or throttle to a slow or zero speed position. There is a need for an electric walk behind greens mower that cannot pull forward suddenly from a stopped position. There also is a need for an electric walk behind greens mower with an automatic slow down system that does not require lifting or pitching of the cutting reel at each turn around.
In the past, the range of most battery powered walk behind greens mowers has been limited to eight or nine greens. Improvements in battery technology may extend the range, but there also is a need to improve the electrical systems of walk behind greens mowers to extend the range even further. The electrical systems of some walk behind greens mowers do not conserve battery power effectively. For example, the pair of motor controllers on most walk behind greens mowers may consume 120 mA current at 50V, which is 6 Watts continuous power, even when the electric motors are not running. Additionally, the contactors on most walk behind greens mowers consume continuous current while the mower is on. There is a need for an electric walk behind greens mower that can extend or conserve battery power to enhance the range of the mower.